ffmpeg

[Parsix]

 

how to view video stream from "Tee pseudo-muxer" in ffmpeg inside gui form?

capture from camera

Quote

ffmpeg -f dshow -i video="WebCamera":audio="Microphone (WebCamera)" -vcodec libx264 -framerate 30 -s 1280x720 -b:a 320k -ar 48000 -ac 2 -t 10 "E:\0-Dev-Projects\0-TestArea\Camera\ffmpeg\output.mkv"

I want to have a live view while recording from the camera.

I used WebcamDS (DirectShow webcam) but it doesn't support x265 with synchronized audio in mp4 output format

[KaFu]

Google AI give me this:

ffmpeg -f dshow -framerate 30 -video_size 1280x720 -i video="WebCamera":audio="Microphone (WebCamera)" -filter_complex "[0:v]split=2[v1][v2]" -map "[v1]" -map 0:a -vcodec libx264 -b:a 320k -ar 48000 -ac 2 -t 10 "E:\0-Dev-Projects\0-TestArea\Camera\ffmpeg\output.mkv" -map "[v2]" -f matroska - | ffplay -i -

[Parsix]

The problem is the display in the autoit form.

this worked

Quote

ffmpeg -f dshow -i video="WebCamera":audio="Microphone (WebCamera)" -vcodec libx264 -framerate 30 -s 1280x720 -b:a 320k -ar 48000 -ac 2 -y "E:\0-Dev-Projects\0-TestArea\Camera\ffmpeg\TEST-1.mkv" -f  matroska -c copy - | ffplay -f matroska -x 760 -y 360 -

 

Edited Friday at 11:15 AM by Parsix

[UEZ]

Try this:

expandcollapse popup

;Code by UEZ build 2026-06-27

#include <AutoItConstants.au3>
#include <GUIConstantsEx.au3>
#include <WindowsConstants.au3>
#include <WinAPIError.au3>

Global $iW = 1280, $iH = 720

Global $sFFMPEG = '"...\FFMPEG\bin\ffmpeg.exe"'
Global $sMPV    = '"...\MPV\mpv.exe"'
Global $sOutFile = "C:\Temp\WebCamRec.mkv"

Global $aVid, $aAud
_GetDShowDevices($sFFMPEG, $aVid, $aAud)
If $aVid[0] = 0 Then Exit MsgBox(16, "Error", "No video capture device found")
Global $sVideo = $aVid[1]                        ; first WebCam
Global $sAudio = ($aAud[0] > 0) ? $aAud[1] : ""  ; first micro, if available
Global $bHasAudio = ($sAudio <> "")

; Input-Optionen MUESSEN vor dem -i stehen (gelten fuer den folgenden Input)
Global $sInput = '-f dshow -rtbufsize 256M -video_size 1280x720 -framerate 30 -pixel_format nv12 ' & _
        '-use_wallclock_as_timestamps 1 -i video="' & $sVideo & '"'
If $bHasAudio Then $sInput &= ' -f dshow -use_wallclock_as_timestamps 1 -i audio="' & $sAudio & '"'
Global $sAudioMap = $bHasAudio ? '-map 1:a -c:a aac -ar 48000 -ac 2 ' : ''

Global $hGUI = GUICreate("WebCam + Live Preview + Record", $iW, $iH + 40, -1, -1, BitOR($WS_OVERLAPPEDWINDOW, $WS_CLIPCHILDREN))
Global $idStop = GUICtrlCreateButton("Stop", 10, $iH + 6, 80, 26)

Global $hChild = GUICreate("", $iW, $iH, 0, 0, $WS_CHILD, -1, $hGUI)
GUISetState(@SW_SHOW, $hChild)
GUISwitch($hGUI)
GUISetState(@SW_SHOW, $hGUI)

Global $wid = Number($hChild)

If FileExists($sOutFile) Then FileDelete($sOutFile)

Global $sUDP = "udp://127.0.0.1:1234?pkt_size=1316"

Global $sCmd =  $sFFMPEG & ' ' & $sInput & ' ' & _
                '-filter_complex "[0:v]split[rec][tmp];[tmp]fps=30[prev]" ' & _
                '-map "[rec]" -c:v libx264 -pix_fmt yuv420p ' & $sAudioMap & '"' & $sOutFile & '" ' & _
                '-map "[prev]" -c:v libx264 -preset ultrafast -tune zerolatency -g 10 -an ' & _
                '-fflags +nobuffer -flags +low_delay -muxdelay 0 -muxpreload 0 -flush_packets 1 ' & _
                '-f mpegts ' & $sUDP

Global $iPID = Run($sCmd, "", @SW_HIDE, $STDIN_CHILD)

Global $sMpvPipe = "\\.\pipe\mpv_preview"
Global $sMpvCmd = $sMPV & ' --wid=' & $wid & ' --no-audio --no-osc --force-window=yes ' & _
                  '--profile=low-latency --untimed --no-cache --demuxer-readahead-secs=0 ' & _
                  '--vd-queue-enable=no --demuxer-lavf-o=fflags=+nobuffer ' & _
                  '--demuxer-lavf-format=mpegts --input-ipc-server=' & $sMpvPipe & ' "' & $sUDP & '"'
                  
Global $iPIDmpv = Run($sMpvCmd, "")

While 1
    Switch GUIGetMsg()
        Case $GUI_EVENT_CLOSE, $idStop
            _StopAll($iPID, $iPIDmpv)
            ExitLoop
    EndSwitch
WEnd
GUIDelete($hGUI)

Func _GetDShowDevices($sFFMPEG, ByRef $aVideo, ByRef $aAudio)
    Local $sExe = StringReplace($sFFMPEG, '"', '')
    Local $iPID = Run('"' & $sExe & '" -hide_banner -list_devices true -f dshow -i dummy', "", @SW_HIDE, $STDERR_CHILD)
    Local $sOut = ""
    While 1
        $sOut &= StderrRead($iPID)
        If @error Then ExitLoop
    WEnd
    Local $aV[1] = [0], $aA[1] = [0], $sType = ""
    Local $aLines = StringSplit(StringStripCR($sOut), @LF), $sLine, $aM
    For $i = 1 To $aLines[0]
        $sLine = $aLines[$i]
        If StringInStr($sLine, "(video)") Then $sType = "v"
        If StringInStr($sLine, "(audio)") Then $sType = "a"
        If StringInStr($sLine, "Alternative name") Then ContinueLoop
        $aM = StringRegExp($sLine, '"([^"]+)"', 1)
        If @error Then ContinueLoop
        If $sType = "v" Then
            _ArrayAdd_($aV, $aM[0])
        ElseIf $sType = "a" Then
            _ArrayAdd_($aA, $aM[0])
        EndIf
    Next
    $aVideo = $aV
    $aAudio = $aA
EndFunc

Func _ArrayAdd_(ByRef $a, $v)
    ReDim $a[$a[0] + 2]
    $a[0] += 1
    $a[$a[0]] = $v
EndFunc

Func _StopAll($iPID, $iPIDmpv)
    If ProcessExists($iPID) Then
        StdinWrite($iPID, "q")
        StdinWrite($iPID)            
        ProcessWaitClose($iPID, 10)  
        If ProcessExists($iPID) Then ProcessClose($iPID) 
    EndIf

    Local $h = FileOpen($sMpvPipe, 2)
    If $h <> -1 Then
        FileWrite($h, '{"command":["quit"]}' & @LF)
        FileClose($h)
    EndIf
    ProcessWaitClose($iPIDmpv, 2)
    If ProcessExists($iPIDmpv) Then ProcessClose($iPIDmpv)
EndFunc

mpv can be found here: https://sourceforge.net/projects/mpv-player-windows/files/

 

Adjust the pathes to ffmpeg and mpv!

Edited 11 hours ago by UEZ
Code update

[Parsix]

Invalid input file index: 1.
Failed to set value '1:a' for option 'map': Invalid argument
Error parsing options for output file C:\temp\WebCamRec.mkv.
Error opening o

 

[UEZ]

39 minutes ago, Parsix said:

Invalid input file index: 1.
Failed to set value '1:a' for option 'map': Invalid argument
Error parsing options for output file C:\temp\WebCamRec.mkv.
Error opening o

 

Made some updates - please try again.

[Parsix]

 

this error :

[in#0 @ 000001ff3283f740] Could not set video options
[in#0 @ 000001ff32845780] Error opening input: I/O error
Error opening input file video=WebCamera.
Error opening input files: I/O error

i modify to this and not have error (ffmpeg)

Global $sAudioMap = ($sAudio <> "") ? '-map 0:a -c:a aac -ar 48000 -ac 2 ' : ''
$sInput = '-f dshow -i video="Camera":audio="Microphone (Camera)" -rtbufsize 256M -video_size 1280x720 -framerate 30 -pixel_format nv12  -use_wallclock_as_timestamps 1'
Global $sCmd = $sFFMPEG & ' ' & $sInput & ' ' & _
               '-filter_complex "[0:v]split[rec][tmp];[tmp]fps=30[prev]" ' & _
               '-map "[rec]" -c:v libx264 -pix_fmt yuv420p ' & $sAudioMap & '"' & $sOutFile & '" ' & _
               '-map "[prev]" -c:v mpeg2video -q:v 5 -an -f mpegts ' & $sUDP

 

but mpv.exe not work

[Parsix]

Sorry, access was blocked by the firewall. The playback was successful, but the playback speed is very slow and there is a lot of delay.

Thank you Dear UEZ, all the best to you always.

 

Edited Friday at 11:11 PM by Parsix

[UEZ]

I updated the code above - the latency should be better now.

[Parsix]

The delay is still noticeable. It doesn't record the last few seconds before pressing the stop button. 

 

Edited 18 hours ago by Parsix

[UEZ]

6 hours ago, Parsix said:

The delay is still noticeable. It doesn't record the last few seconds before pressing the stop button. 

 

Last try - see above.

Personally, I don't like this approach of using ffmpeg and mpv to display and record the webcam.